September 22, 2010

Initial success in gopher tortoise relocation project

Aiken Gopher Tortoise Heritage Preserve’s (AGTHP) gopher tortoise relocation project is beginning to show signs of successful site fidelity and survivorship. Successful reproduction was also documented this year and a head-start program was initiated. These are critical components of establishing a viable self-sustaining population.

Researchers Kurt Buhlmann, Tracey Tuberville, and Andrew Grosse from Savannah River Ecology Laboratory (SREL) and wildlife biologist Brett M. Moule with the S.C. Department of Natural Resources (DNR) recently began nests checks at AGTHP. Teams split-up and delicately excavated the entrances of each burrow with trowels. With great surprise and delight, they began unearthing hatched, unhatched, and hatching eggs. There was a mix of unsuccessful and successful clutches. Tuberville has collected blood samples from each gopher tortoise released on the property since the beginning of the project, which will facilitate determination of maternal and paternal origins of each offspring.

Both the hatchlings and any viable eggs were transported to SREL to be marked or placed into an incubator to allow for future development. They were returned and released at AGTHP after marking and completing the required lab tests on the hatchlings.

Another unique observation made by the team, and captured on video, was of a female displaying nest guarding behavior which is not commonly observed among turtles. Tortoises are long-lived, slow to reproduce, and experience high mortality during the juvenile stage although the team is documenting initial signs of successful site fidelity, survivorship, and reproduction.

The team will continue to augment the AGTHP population with trans-located gopher tortoises as the adult population is still small and there is enough unoccupied suitable habitat to support many more tortoises.

The gopher tortoise is the only species of tortoise found in the eastern United States and one of only four tortoise species found in North America. Tortoise burrows are not just important to the tortoises, but are also a critical resource for many species that are found in sandhill habitats. Over 250 species of vertebrate and invertebrate animals have been documented to use tortoise burrows, whether active or abandoned.

Currently, the primary challenge to the gopher tortoise is habitat loss, either through direct means, such as type conversion to loblolly plantations, agriculture or development; or through indirect means, such as fire suppression that results in successional changes that render the habitat unsuitable for tortoises.